Naaaaaaaa! Never Happened. I have a few of these old brown/yellow/orange mottled U-293 porcelain signals that have a fascinating splash of colors in the glaze. So...I got to fooling around with my craft paints and tried to mimic the U-293 by painting a worthless clear glass Hemingray CD 163 to look similar.
All went well until I baked the paint and let the glass get a little too hot, It is now a 2 piece and has a clean break all the way around the center of the wire groove. The small embossed letters sure look odd on a mud insulator! For you Hemingray date dot freaks, it is a 1953. I can hardly think of a more worthless insulator than a clear CD 163 ! But I will take all that anyone can give me. and at least a gallon of craft paint .